I'll keep posting in this thread, as what I want is design related also.
I did these changes myself, but I'd like them integrated into the main plugin:
1. Remove the box-shadow style. It makes the bar look beveled and it looks bad.
2. Make the inner divs 100% and keep only the main div (wppb-wrapper) fixed width. Or 100%, depending on your "responsiveness" decision from the other thread.
3. Add an option to the control panel for width: Either choose 100% or a fixed width in pixels. I discovered 400px looks a bit short on my site, and 100% looks great. This is my site - http://getbutterfly.com/ - the progress bars are on the front page.
4. Normal text (instead of bold) for percentage value.
I know that design and appearance is pretty subjective, but I think (and again, I'm subjective) my points above are valid.